This invention relates to automatic packaging machines and more particularly to method of and means for folding, forming and closing self-latching boxes with a flip top.
Reference is made to the following U.S. Patents, assigned to the assignee of this invention, which provide background information on automatic packaging machines: U.S. Pat. Nos. 4,578,929; 4,548,593; 4,716,714; 4,829,751; 4,856,566; 4,982,556; 5,010,929; 5,072,573; and 5,144,790. Co-pending U.S. patent application Ser. Nos. 08/848,127 filed Apr. 27, 1997 and 08/856,443 filed May 14, 1997 are examples of a type of packaging machines which may be used to load small items, such as candy-coated chewing gum into a different kind of box.
Conventional automatic packing machines have a conveyor, usually an endless link chain conveyor, which travels through or past a number of work stations extending between a magazine containing package blanks and a product discharge end. Usually, the package blanks are a stack of die cut cardboard blanks which are picked up one-at-a-time by vacuum cups and then put into box forming mandrels carried by the conveyor. Tabs and flaps on the bottom of the blank are folded by plows and sealed in order to close the box. Then a pre-determined amount of product is placed in the box. Next, tabs and flaps forming a top of the box are folded and sealed. Then the box is discharged on to any suitable conveyor, into a shipping carton, or to another device for receiving the completed product containing packaging.
Conventionally, a plow is a strip of metal, or the like, extending along a length of the conveyor and in a location where the tabs and flaps are to be folded. First, tabs and flaps forming the bottom of the box encounter the plows and they are folded as the conveyor carries the box past the plow. Then, a pre-determined amount of product is placed in the box. Next, tabs and flaps forming a top of the box are folded and sealed in a similar manner. Depending upon product packaging needs, the box may or may not be wrapped in a transparent film which is sealed. Finally, the box is discharged on to any suitable conveyor, into a shipping box or to another suitable device for receiving the product containing packaging.
Often, the product presents special considerations which require the packaging machine to perform unique functions as the box is formed and filled. These functions may be performed by special parts which are attached to or positioned near the conveyor. Many examples of such special parts are shown and described in the above-cited patents.
This invention is directed to a problem which is exemplified by a xe2x80x9cflip-topxe2x80x9d box for small items, such as candy coated chewing gum or the like. Such a box is made from a single, unitary, die cut blank of thin cardboard stock. A flip-top box has a bottom section is in the form of a rectangular parallelepiped. The top of the box is in the form of a hood connected to the bottom along a crease line which acts as a hinge. The hood moves away from or over the top of the box in order to open or close it. It is necessary for the packaging machine to first form the blank into the box, then count a specific number of small item, here candy coated chewing gum, next deposit them in the box, and finally close and seal the box.
One particular box requiring a unique treatment has a number of tabs which are folded in such a manner that the flip-top is xe2x80x9clatchedxe2x80x9d in a closed position and yet is easily opened, closed, and relatched with only a small amount of force. This invention relates to a packaging machine for folding and sealing the various flap and tabs which form the latching flip-top.
In keeping with an aspect of the invention, a plurality of mandrels are bolted to an endless link chain conveyor. The mandrel has two parts, one of which is hinged to the other with a coiled spring bias urging the two parts away from each other and into a normal or straight configuration. A first of the two parts is bolted in a fixed position to and immobilized on the conveyor link chain. The second and hinged part of the mandrel has a roller thereon which rides in a cam track located adjacent a portion of the link chain conveyor in order to articulate the hinged section part to a somewhat right angle configuration over the first part in order to form and close the flip-top of the box. Plows alongside the conveyor press tabs into place where they are secured by glue, thereby forming the flip-top. The plows also press a latching tab into a loosely folded position where it is caught by the tabs on the flip-top, thereby creating a latching condition.